This threshold ramp is 4 inches high and is a lightweight yet durable modular ramp designed to get your scooter or wheelchair across doorways, sliding glass doors and other raised landings. Threshold ramps may be used either one by itself or two combined to make entry and/or exit convenient and safe. Simply measure the height of the door entry and choose the correct size. They are constructed of extruded, anodized aluminum that will not rust or corrode.